Use correct chess terms + fix spelling.

- "discovered check" (instead of "discovery check")
  - "en passant" (instead of "en-passant")
  - "pseudo-legal" before a noun (instead of "pseudo legal")
  - "3-fold" (instead of "3fold")

closes https://github.com/official-stockfish/Stockfish/pull/3294

No functional change.

AUTHORS

@@ -46,6 +46,7 @@ Dariusz Orzechowski (dorzechowski)
 David Zar
 Daylen Yang (daylen)
 Deshawn Mohan-Smith (GoldenRare)
+Dieter Dobbelaere (ddobbelaere)
 DiscanX
 Dominik Schlösser (domschl)
 double-beep

src/movegen.cpp

@@ -85,7 +85,7 @@ namespace {
 
             // Add pawn pushes which give discovered check. This is possible only
             // if the pawn is not on the same file as the enemy king, because we
-            // don't generate captures. Note that a possible discovery check
+            // don't generate captures. Note that a possible discovered check
             // promotion has been already generated amongst the captures.
             Bitboard dcCandidateQuiets = pos.blockers_for_king(Them) & pawnsNotOn7;
             if (dcCandidateQuiets)
@@ -134,7 +134,7 @@ namespace {
             moveList = make_promotions<Type, Up     >(moveList, pop_lsb(&b3), ksq);
     }
 
-    // Standard and en-passant captures
+    // Standard and en passant captures
     if (Type == CAPTURES || Type == EVASIONS || Type == NON_EVASIONS)
     {
         Bitboard b1 = shift<UpRight>(pawnsNotOn7) & enemies;
@@ -167,7 +167,7 @@ namespace {
             assert(b1);
 
             while (b1)
-                *moveList++ = make<ENPASSANT>(pop_lsb(&b1), pos.ep_square());
+                *moveList++ = make<EN_PASSANT>(pop_lsb(&b1), pos.ep_square());
         }
     }
 
@@ -355,7 +355,7 @@ ExtMove* generate<LEGAL>(const Position& pos, ExtMove* moveList) {
   moveList = pos.checkers() ? generate<EVASIONS    >(pos, moveList)
                             : generate<NON_EVASIONS>(pos, moveList);
   while (cur != moveList)
-      if (   (pinned || from_sq(*cur) == ksq || type_of(*cur) == ENPASSANT)
+      if (   (pinned || from_sq(*cur) == ksq || type_of(*cur) == EN_PASSANT)
           && !pos.legal(*cur))
           *cur = (--moveList)->move;
       else

src/movepick.cpp

@@ -142,7 +142,7 @@ Move MovePicker::select(Pred filter) {
 }
 
 /// MovePicker::next_move() is the most important method of the MovePicker class. It
-/// returns a new pseudo legal move every time it is called until there are no more
+/// returns a new pseudo-legal move every time it is called until there are no more
 /// moves left, picking the move with the highest score from a list of generated moves.
 Move MovePicker::next_move(bool skipQuiets) {
 

src/movepick.h

@@ -108,9 +108,9 @@ typedef Stats<int16_t, 29952, PIECE_NB, SQUARE_NB> PieceToHistory;
 typedef Stats<PieceToHistory, NOT_USED, PIECE_NB, SQUARE_NB> ContinuationHistory;
 
 
-/// MovePicker class is used to pick one pseudo legal move at a time from the
+/// MovePicker class is used to pick one pseudo-legal move at a time from the
 /// current position. The most important method is next_move(), which returns a
-/// new pseudo legal move each time it is called, until there are no moves left,
+/// new pseudo-legal move each time it is called, until there are no moves left,
 /// when MOVE_NONE is returned. In order to improve the efficiency of the alpha
 /// beta algorithm, MovePicker attempts to return the moves which are most likely
 /// to get a cut-off first.

src/position.cpp

@@ -505,7 +505,7 @@ bool Position::legal(Move m) const {
   // En passant captures are a tricky special case. Because they are rather
   // uncommon, we do it simply by testing whether the king is attacked after
   // the move is made.
-  if (type_of(m) == ENPASSANT)
+  if (type_of(m) == EN_PASSANT)
   {
       Square ksq = square<KING>(us);
       Square capsq = to - pawn_push(us);
@@ -655,7 +655,7 @@ bool Position::gives_check(Move m) const {
   // of direct checks and ordinary discovered check, so the only case we
   // need to handle is the unusual case of a discovered check through
   // the captured pawn.
-  case ENPASSANT:
+  case EN_PASSANT:
   {
       Square capsq = make_square(file_of(to), rank_of(from));
       Bitboard b = (pieces() ^ from ^ capsq) | to;
@@ -716,7 +716,7 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
   Square from = from_sq(m);
   Square to = to_sq(m);
   Piece pc = piece_on(from);
-  Piece captured = type_of(m) == ENPASSANT ? make_piece(them, PAWN) : piece_on(to);
+  Piece captured = type_of(m) == EN_PASSANT ? make_piece(them, PAWN) : piece_on(to);
 
   assert(color_of(pc) == us);
   assert(captured == NO_PIECE || color_of(captured) == (type_of(m) != CASTLING ? them : us));
@@ -742,7 +742,7 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
       // update non-pawn material.
       if (type_of(captured) == PAWN)
       {
-          if (type_of(m) == ENPASSANT)
+          if (type_of(m) == EN_PASSANT)
           {
               capsq -= pawn_push(us);
 
@@ -769,7 +769,7 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
       // Update board and piece lists
       remove_piece(capsq);
 
-      if (type_of(m) == ENPASSANT)
+      if (type_of(m) == EN_PASSANT)
           board[capsq] = NO_PIECE;
 
       // Update material hash key and prefetch access to materialTable
@@ -815,7 +815,7 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
   // If the moving piece is a pawn do some special extra work
   if (type_of(pc) == PAWN)
   {
-      // Set en-passant square if the moved pawn can be captured
+      // Set en passant square if the moved pawn can be captured
       if (   (int(to) ^ int(from)) == 16
           && (pawn_attacks_bb(us, to - pawn_push(us)) & pieces(them, PAWN)))
       {
@@ -938,7 +938,7 @@ void Position::undo_move(Move m) {
       {
           Square capsq = to;
 
-          if (type_of(m) == ENPASSANT)
+          if (type_of(m) == EN_PASSANT)
           {
               capsq -= pawn_push(us);
 
@@ -1042,7 +1042,7 @@ void Position::undo_null_move() {
 
 /// Position::key_after() computes the new hash key after the given move. Needed
 /// for speculative prefetch. It doesn't recognize special moves like castling,
-/// en-passant and promotions.
+/// en passant and promotions.
 
 Key Position::key_after(Move m) const {
 

src/position.h

@@ -113,7 +113,7 @@ public:
   Bitboard blockers_for_king(Color c) const;
   Bitboard check_squares(PieceType pt) const;
   Bitboard pinners(Color c) const;
-  bool is_discovery_check_on_king(Color c, Move m) const;
+  bool is_discovered_check_on_king(Color c, Move m) const;
 
   // Attacks to/from a given square
   Bitboard attackers_to(Square s) const;
@@ -304,7 +304,7 @@ inline Bitboard Position::check_squares(PieceType pt) const {
   return st->checkSquares[pt];
 }
 
-inline bool Position::is_discovery_check_on_king(Color c, Move m) const {
+inline bool Position::is_discovered_check_on_king(Color c, Move m) const {
   return st->blockersForKing[c] & from_sq(m);
 }
 
@@ -371,7 +371,7 @@ inline bool Position::capture_or_promotion(Move m) const {
 inline bool Position::capture(Move m) const {
   assert(is_ok(m));
   // Castling is encoded as "king captures rook"
-  return (!empty(to_sq(m)) && type_of(m) != CASTLING) || type_of(m) == ENPASSANT;
+  return (!empty(to_sq(m)) && type_of(m) != CASTLING) || type_of(m) == EN_PASSANT;
 }
 
 inline Piece Position::captured_piece() const {

src/search.cpp

@@ -84,7 +84,7 @@ namespace {
     return d > 14 ? 29 : 8 * d * d + 224 * d - 215;
   }
 
-  // Add a small random component to draw evaluations to avoid 3fold-blindness
+  // Add a small random component to draw evaluations to avoid 3-fold blindness
   Value value_draw(Thread* thisThread) {
     return VALUE_DRAW + Value(2 * (thisThread->nodes & 1) - 1);
   }
@@ -1127,7 +1127,7 @@ moves_loop: // When in check, search starts from here
 
       // Check extension (~2 Elo)
       else if (    givesCheck
-               && (pos.is_discovery_check_on_king(~us, move) || pos.see_ge(move)))
+               && (pos.is_discovered_check_on_king(~us, move) || pos.see_ge(move)))
           extension = 1;
 
       // Last captures extension
@@ -1541,7 +1541,7 @@ moves_loop: // When in check, search starts from here
           &&  futilityBase > -VALUE_KNOWN_WIN
           && !pos.advanced_pawn_push(move))
       {
-          assert(type_of(move) != ENPASSANT); // Due to !pos.advanced_pawn_push
+          assert(type_of(move) != EN_PASSANT); // Due to !pos.advanced_pawn_push
 
           // moveCount pruning
           if (moveCount > 2)

src/types.h

@@ -113,7 +113,7 @@ constexpr int MAX_PLY   = 246;
 /// bit  6-11: origin square (from 0 to 63)
 /// bit 12-13: promotion piece type - 2 (from KNIGHT-2 to QUEEN-2)
 /// bit 14-15: special move flag: promotion (1), en passant (2), castling (3)
-/// NOTE: EN-PASSANT bit is set only when a pawn can be captured
+/// NOTE: en passant bit is set only when a pawn can be captured
 ///
 /// Special cases are MOVE_NONE and MOVE_NULL. We can sneak these in because in
 /// any normal move destination square is always different from origin square
@@ -127,7 +127,7 @@ enum Move : int {
 enum MoveType {
   NORMAL,
   PROMOTION = 1 << 14,
-  ENPASSANT = 2 << 14,
+  EN_PASSANT = 2 << 14,
   CASTLING  = 3 << 14
 };